As a by-product, municipal waste-treatment plants generate high quantities of sewage sludge whose disposal is highly cost intensive. However, only around one third is eliminated in today‘s standard sludge-digestion processes.

Our Idea and Solution

To avoid high quantities of sludge, the effluent is fermented by methanising the organic contaminants anaerobically initially through immobilised microorganisms and subsequently aerobically aftertreated. In the process, the contents of effluent are largely eliminated with much lower sludge production.

Description of Process

In the first anoxic, downstream chamber, the organic content of the effluent is subject to hydrolysis and acidification. From here, the effluent flows into the plant’s anaerobic reactor and then upstream through a layer of immobilised anaerobic microorganisms equipped with absorbing, porous LEVAPOR carriers which degrade the "broken down" organic substances by methanisation. The generated biogas is collected in the upper section of the reactor and released into the environment. The anaerobically pre-treated effluent, 65 to 80 percent of whose organic load has already been eliminated, flows through an overflow into the aerobic reactor, which is aerated by means of a special ventilation system installed on the ground. The residual organic contaminants are then oxidised to form carbon dioxide and the ammonium nitrate is nitrified to form nitrate. The denitrification to molecular nitrogen is effected in non-aerated, oxygen-poor segments of the activated reactor.

The excess sludge produced there, comprising generally only 1/5 to 1/4 of the normal amount, is then separated off into a secondary tank and removed from the plant at regular intervals.

The advantages of the anaerobic-aerobic process compared with the aerobic variant: · Maximum possible elimination performance, with

Lower energy consumption (for aeration and sludge treatment). In addition, by virtue of the microorganisms immobilised on LEVAPOR considerably more hazardous, endocrine disrupters could be eliminated than in the parallel plant operating with suspended organisms.

The advantages of our carrier material LEVAPOR

The carrier medium LEVAPOR is a new technology offered exclusively by Biocons (patent).